'84 Sierra has funny brake pedal...

Hello all...

Just last week my trusty (and certainly rusty!) '84 Sierra w/ 6.2 started playing games with the brake pedal. At all times I have "good" power brakes and I can lock the tires up and slide even when the pedal is misbehaving.

What happens: At times the pedal works properly and is firm. Braking action starts very soon and seems to work fine. Other times the pedal goes waaaay down (but not anywhere near "bottomed out") before braking action takes place. There doesn't seem to be a rhyme or reason to this behavior. I can use the brakes quickly with less than a second's pause and while the first use may have long pedal travel, the second use is fine. It does not matter if the truck has been running at highway speeds or if has been sitting idling for a while.

As best I can tell, all of the front brakes, the fluid and the belt driving the vacuum/PS pump seem to be in fine shape. I have not checked the back brakes due to lack of time.

Can anyone say what might be going on here? I'd really appreciate some assistance or thoughts...

William The Guesser

Reply to
William R. Walsh
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sounds like the master cylinder is bad.

Reply to
Scott M

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Time for a master cylinder. Not a big job and only a $50 part but be sure you read the instruction on how to bench bleed it. Should take you an hour tops.

good luck, mark

Reply to
rock_doctor

I'd have to agree with Scott... The valving in the master cylinder is likely going bad.

It's not too big of a deal to replace. Pop the lines off, inbolt it from the booster, bench bleed the new one and install it on the booster, re-hook the lines, then bleed the entire brake system.

Dunno how much they want for it at AutoZone or Advance, but I only go to Bumper-To-Bumper or Jopac for parts anymore. Seems like they have similar prices, and know a hell of alot more than the retards that the other places hire.

-Tony

Reply to
Tony Kimmell

Hi!

Well, I figured that I might just "deal with it" for a while as the truck still did stop...but it gave me a big warning the other day. I backed out of my driveway and discovered to my horror that there were no brakes at all. Thankfully I had fixed the emergency brake and it did work. Now the truck has gone from having some brakes most times to having nearly poor to no power brakes at idle and good brakes when coming down from a "high speed " run.

I must say don't know what's wrong now and won't be driving the truck until I can fix it. I may just pay a local mechanic to deal with it. I don't have lots of spare time these days... Brakes aren't something I'm really willing to screw around with anyway.

How does one bench bleed something? I'm not familiar with the process...

I could tell a story about that. Left the lights on in my old truck and ruined one of the batteries. Went to AutoZone for another because it was handy. Long story short, the Wal-Mart batteries the truck had in it have lasted the longest of any battery it's ever had. So when the bozo at AutoZone said "I know what your problem is...it's printed on the battery..." I really wanted to turn around and leave. Had there not been another clerk (this one with manners) there when I came back, I would have given Wal-Mart the business again...

Rant mode off...

William The Guesser

Reply to
William R. Walsh

Then it wont be "all you". Never seen you give up yet, you have that purdy S10/Sonoma - do it your self.

He said the instructions would be in the box w/ the part.

If you want a good batt for ye' ol' Jimmy get an AC Delco battery. My father generally get's 8 to 10 years, and their warranty is 6 years on it's own!

GMC Gremlin

Reply to
GMC Gremlin

X-No-Archive: yes

Way1: The new master cylinder should come with little plastic plugs and hoses attached. You install the master cylinder w/o the pressure lines, install the plastic plugs and the hoses will loop around and sit in the fluid reservoir. Fill each chamber with fluid and then climb in and pump the breaks slowly. Keep doing it until you don't see the fluid level go down anymore. Then install pressure lines.

Way2: The second way to bench bleed is to install the master cylinder, fill the reservoir with fluid and have somebody climb into the cab. Put your fingers over the pressure ports and have somebody slowly pump the breaks. When the peddle goes down it will push the air out and because your fingers are over the hole it can't suck the air back in so it stays filled with fluid. Keep doing this until you get all fluid, no air and then install pressure lines.

Way 3: Way three is to put the new master cylinder into a large bench vice. Using the plastic caps and hoses or the finger method use a Phillips screwdriver and push in on the plunger until you get fluid. This method is why they call it bench bleeding. Most people don't have a large jaw vice so I generally suggest the install on the truck and bleed method.

All three ways will take about 10 mins tops...(more like 5). Start the engine and check your peddle level, firmness and make sure it returns to the off position. If the peddle is soft you will need to bleed the entire system which can be done easily with a hand vacuum pump. On the other side of the fence I just had the master cylinder replaced on my suburban. The part was $45 and $60 to install it and flush the entire system. So you have to decide if you would rather spend the $60 labor or do it yourself. I had it done for me... :-)

IMHO there isn't anything wrong with Wal-mart batteries. They are now made by Excide and I have been using Excide auto and marine batteries for more then 15 yrs and have been very happy with every one. Good luck with the truck.

mark

Reply to
rock_doctor

Hi!

No maybe not. But I've never done a great deal of serious brake work. I don't want to discover that when I have to stop that I cannot do so. Still, I might try it and just take it really easy around town until I'm sure the brakes are working right. Obviously there are non-powered brakes, but on this truck they are a joke. A joke that goes like you stamp on the pedal with both feet and beg the truck to stop. Not funny.

I didn't see that, but there was a reason I asked. Sometimes the provided instructions leave something to the imagination.

I've found the Wal-Mart and AC Delco batteries to be the ones I've had the best luck with. The truck has loved to shamelessly destroy such things as Interstate batteries.

William

Reply to
William R. Walsh

Inline....................

Do it yourself, do some panic stops out in a pasture somewhere (you live on a farm right?) and drive on backass roads till you feel comfortable with it.

OK, to bench bleed a master cylinder:

1) Put the MC in a bench vice 2) Fill up both reservoirs with brake fluid 3) Use the bleed kit that came with it (2 threaded plastic nipples, 2 nipple caps, and two small hoses). The threaded nipples go where the brake lines would attach, and you run the hoses back into the reservoir. You're essentialy going to to be pumping the brake fluid out of and right back into the MC 4) Using a LARGE phillips screwdriver, slowly (SLOWLY!!) depress the MC piston. You'll see the air bubbling thru the lines into the reservoir. 5) Repeat #4 until there are no more bubbles. 6) Remove the hoses, use the caps to plug the nipples, put the MC reservoir cover on and it's ready to install.

Take er' easy,

Doc

Reply to
"Doc"

Wow, I would've agreed with the AutoZone tech about Wal-Mart batteries being shit. I used to be the service manager at The Walmart up here in Normal, IL and had plenty of wonderful experiences with those EverStart (Never-Start) batteries.

Although I think the newer ones should be of better quality, as they are no longer made by Johnson Controls. Exide makes them now. If you've had good luck with them, then they were definately the Exide version. The old Johnson Controls batteries were lucky to last 2 years. I quit Wal-Mart right after they switched over, so never really had much experience with the Exides.

The Autozone guy had no room to talk though... Autozone/Duralast batteries are shit too. Maybe I'm just picky, but the only batteries I ever use are Interstate and AC-Delco.

-Tony

Reply to
Tony Kimmell

Hi!

Hmmm...I've heard horror stories from people who bought batteries at the Normal Wal-Mart. I've either been lucky or it's because I bought mine at either Clinton or Champaign. I've had at least four Everstarts now from Johnson Controls and all have performed excellently. All but one is still on the road--the first one I ever bought was for a lawn mower that I rebuilt the engine on and it lasted from 1998 until earlier this year. It didn't die per se, but the mower was very difficult to start with that battery--it just couldn't spin it over fast enough.

The next one is on my fathers '94 Chevy. It's never been treated roughly and has given no trouble.

Another went into my dad's Taurus wagon. A few days after it was installed the dome lights were left on overnight. The battery still started the car the next morning.

Two were in my '84 Sierra and they were the first set of batteries that outlasted almost every stupid thing I ever did to them. They survived a slipping alternator belt, at least 5 or 6 deep discharges over time when the truck sat and very hard starts in the cold. No other battery of any kind has lasted that long in the truck (since mid-December '00) and one of them is still there.

Interstate batteries couldn't stay in that truck, but I think it was more a problem of the people selling them than it was the actual battery's fault. I have one now in an MGB that sat for three years with the battery in it. That battery took a charge right off and has been working fine two years later.

Dunno about the AC-Delco ones for sure--but the one in my '03 S-10 is doing fine and the one that came with my dad's 94 when it was new lasted until

2001. It died of an internal short, but even as it failed it could still start the truck with some patience.

As for the AutoZone battery, I took a chance. I bought the biggest battery they had for my truck and I'm hoping it lasts. Even if it only goes half as long as the Wal-Mart ones I will still be pretty happy and there's an 8-year warranty. Didn't think I could go too wrong with that.

William

Reply to
William R. Walsh

You'll hear horror stories about anything coming out of the Wal-Mart TLE. That's the reason I quit. As soon as I was promoted to manager, the head TLE manager went and hired 5-6 new techs, which knew nothing about working on vehicles. Hell I had to show one of them the "lefty-loosey" rule on an oil plug for God's sake!! Then I got lectured for not being able to make the employees perform well.. told the manager that you can't hire morons and get mad at ME when they screw up. He didn't understand that concept so I found a new job. Wal-Mart just sucks period. The managers are lazy and under-qualified for the job, and all the white-trash morons that work there don't help either.

-Tony (who won't shop at Wal-Mart ever again)

Reply to
Tony Kimmell

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